docs: def yum_search(packages):
      """Search for a package."""
      output = {}
      cmd = ['yum', 'search']
      if isinstance(packages, six.string_types):
          cmd.append(packages)
      else:
          cmd.extend(packages)
      log("Searching for {}".format(packages))
      result = subprocess.check_output(cmd)
      for package in list(packages):
          output[package] = package in result
      return output